Water Content of Greenland Ice Estimated from Ground Radar and Borehole Measurements

Joel Brown, Joel Harper, Neil Humphrey
2016 The Cryosphere Discussions  
Liquid water content (wetness) within glacier ice is known to strongly control ice viscosity and ice deformation processes. Little is known about wetness of ice on the outer flanks of the Greenland ice sheet, where a temperate layer of basal ice exists. This study integrates borehole and radar surveys to provide direct estimates of englacial ice wetness in the ablation zone of western Greenland. We estimate electromagnetic propagation velocity of the ice body by inverting reflection traveltimes
more » ... lection traveltimes from radar data. Our inversion is constrained by ice thickness measured in boreholes and by positioning of a temperate/cold ice boundary identified in boreholes. Electromagnetic propagation velocities are consistent with a depth-averaged wetness of ~&amp;thinsp;0.5&amp;ndash;1.1&amp;thinsp;%. The inversion indicates that wetness within the ice varies from <&amp;thinsp;0.1&amp;thinsp;% in an upper cold layer to ~&amp;thinsp;2.9&amp;ndash;4.6&amp;thinsp;% in a 130&amp;ndash;150&amp;thinsp;m thick temperate layer located above the glacier bed. Such high wetness should yield high rates of shear strain.
doi:10.5194/tc-2016-208 fatcat:2aqa4v2qtbbffhpqd2bgxiuhwa